1. Field of the Invention
This invention relates to polyamides, and processes for making and using the same. In particular, the polyamide is an enzymatic reaction product of a polyamine and diester. The present invention is further directed to cellulose products as well as creping adhesives and wet strength resins comprising the enzymatic reaction product, and processes for preparing the same.
2. Background of the Invention and Related Information
Polyamides are extensively used in the papermaking industry as wet strength agents or creping aids in the production of tissue and towel paper products. The polyamides are usually synthesized via chemical processes using chemical catalysts at high temperatures and in the presence of organic solvents. Chemical processes provide an economical means for high production of polymers. However, the chemical catalysts lack the high selectivity required for the production of polymers having suitable properties such as high purity and appropriate molecular weight. Also, chemical production of polymers contributes to pollution throughout and after synthesis [Chaudhary et al., Biotechnol. Prog., 13, 318-325, (1997)].
Enzymes possess high selectivity and fast catalytic rates under mild conditions [Dordick, Ann. N.Y. Acad. Sci., 672, 352-362, (1992)]. The high selectivity reduces side reactions and allows easier separation and/or purification of the desired product. In addition, the ability to catalyze various types of organic reactions under mild conditions (e.g., ambient temperatures and pressure) makes the commercial use of enzymes highly feasible and attractive [Chaudhary et al., Biotechnol. Prog., 13, 318-325, (1997)]. Furthermore, the discovery that enzymes can function in reverse to catalyze esterifications and transesterifications, rather than the customary degradation or hydrolysis, has made enzymatic synthesis a competitive alternative to chemical synthesis of polymers [Dordick, Ann. N.Y. Acad. Sci., 672, 352-362, (1992); Brazwell et al., J. Polym. Sci. Part A: Polym. Chem., 33, 89-95, (1995)].
The enzymatic synthesis of small molecules has been extensively demonstrated using lipase [Djeghaba et al., Tetrahedron Lett., 32, 761-762, (1991); Kanerva et al., Tetrahedron Assymm., 7, 1705-1716, (1996); Vorde et al., Tetrahedron Assym., 7, 1507-1513, (1996)]. Larger molecules, such as polyesters have also been synthesized enzymatically, using lipase as the catalyst and in the absence or presence of organic solvents.
Chaudary et al. [Biotechnol. Prog., 13, 318-325, (1997)] disclose bulk polymerization of polyesters under ambient conditions with low concentrations of biocatalyst.
Brazwell et al. [J. Polym. Sci. Part A: Polym. Chem., 33, 89-95, (1995)] describe enzyme-catalyzed polycondensation with pig pancreas lipase to produce aliphatic polyesters.
Linko et al. [Enzyme Microb. Technol., 17, 506-511, (1995)] describe the enzymatic polymerization of bis(2,2,2-trifluoroethyl) sebacate and aliphatic diols in a transesterification reaction to produce linear polyesters.
Binns et al. [J. Chem. Soc. Perkin Trans., 1, 899-904, (1993)] describe the enzymatic synthesis of a low-dispersity polyester from the polyesterification of adipic acid and butane-1,4-diol by a commercial lipase.
Geresh et al. [Biotechnol. Bioeng., 37, 883-888, (1991)] describe the synthesis of unsaturated polyesters using lipases from different sources and in two different organic solvents, acetonitrile and tetrahydrofuran.
Additionally, WO 94/12652 discloses the enzymatic synthesis of polyesters or polyester(amide)s in the absence of solvent and presence of lipase.
Despite the numerous chemical methods for producing polyamides, there still remains a need in the art for preparing polyamides that will provide relatively pure, high molecular weight polyamides in high yields.
The present invention relates to polyamides, and processes for preparing and using the same. The polyamide of the present invention is the enzymatic reaction product of a polyamine and diester. The present invention has found that enzymatic synthesis of polyamides provides high yields of relatively pure polyamides with high molecular weight.
In particular, the present invention is advantageous in providing a highly selective enzymatic process for the synthesis of polyamides with high molecular weight under mild conditions and without the need for extraneous solvents. In addition, the enzyme may be optionally recycled for further use.
The present invention provides a process for preparing a polyamide which comprises reacting at least one diester and at least one polyamine in the presence of hydrolytic enzyme wherein the hydrolytic enzyme is at least about 0.01% by weight based on the total weight of the diester and polyamine, and
the diester has the following general formula:
R1OOCxe2x80x94Rxe2x80x94COOR2
or
R1OOCxe2x80x94COOR2,
wherein R is a C1 to C20 hydrocarbyl group selected from one of alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; R1 and R2 are C1 to C22 hydrocarbyl group selected from alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; and wherein R1 and R2 may be the same or different; and
the polyamine has the following general formula:
H2Nxe2x80x94R3xe2x80x94[Xxe2x80x94R4]nxe2x80x94NH2,
wherein R3 and R4 are C1 to C6 hydrocarbyl group selected from one of alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; X is selected from one or none of heteroatom or non-heteroatom, wherein the non-heteroatom comprises amine, thiol, carbonyl, carboxyl or C1 to C6 hydrocarbyl group selected from one of alkanol, alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene or alkenyl; n is from 0 to 40; and wherein R3 and R4 may be the same or different.
In one embodiment of the invention, R is a C1 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 to C6 alkyl group, R4 is a C2 to C6 alkyl group, X is CH2, O, S or NH, and n is 1 to 5.
In another embodiment of the invention, R is a C2 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 alkyl group, R4 is a C2 alkyl group, X is NH, and n is 1.
Additionally, the molecular weight of diesters of the present invention preferably range from about 100 to 1200 Daltons and most preferably from about 100 to 300 Daltons.
Suitable diesters of the present invention include dialkyl malonate, dialkyl fumarate, dialkyl maleate, dialkyl adipate, dialkyl glutarate, dialkyl succinate, dialkyl oxalate, dialkyl phenylmalonate or mixtures thereof.
The molecular weight of the polyamines of the present invention is preferably a range from about 40 to 10,000 Daltons and most preferably from about 40 to 2500 Daltons.
Suitable polyamines of the present invention include ethylenediamine (EDA), triethylene glycol diamine, bishexamethylenediamine (BHMT), hexamethylenediamine (HMDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), dipropylenetriamine (DPTA), tripropylenetetramine (TPTA), tetrapropylenepentamine (TPPA), N-methyl-bis-(aminopropyl)amine (MBAPA), spermine, spermidine, 1-phenyl-2,4-pentane diamine, 2-phenyl-1,3-propanediamine, phenylene diamine or mixtures thereof.
Enzymes of the present invention are obtained from natural (such as animals, plants, bacteria, yeast, fungi or virus) or synthetic sources (such as peptide synthesizer or expression vector). Natural sources include Candida species (such as Candida antarctica), Pseudomonas species (such as Pseudomonas fluorescens or Mucor species (such as Mucor miehei).
Suitable hydrolytic enzymes of the present invention are free or immobilized and include lipase, esterase or protease.
The hydrolytic enzyme is present in an amount preferably from about 0.01% to 10%, more preferably from about 0.1% to 5%, and most preferably from about 0.5% to 3% by weight based on the total weight of the diester and polyamine.
The hydrolytic enzyme of the present invention may be removed or denatured.
The molar ratio of the reactant ester group of the diester: reactant primary group of the amine group of the polyamine is preferably from about 0.8:2.0 to 2:0.8, and most preferably from about 0.95:1.1 to 1.1:0.95.
In one embodiment of the invention, the molar ratio of the reactant ester group of the diester:reactant primary group of the amine group of the polyamine is preferably from about 1:1.01 to 1:2, and most preferably from about 1:1.03 to 1:1.06.
The polyamide of the present invention may be present in aqueous solution at a final concentration of preferably greater than about 1% by weight and most preferably greater than about 40% by weight.
Polyamides of the present invention have a molecular weight polydispersity (Mw/Mn) from about 1.2 to 5.0 and most preferably from about 2.2 to 3.0.
Accordingly, the polyamides of the present invention have a molecular weight range preferably from about 1,000 to 60,000 Daltons, and most preferably from about 4,000 to 12,000 Daltons.
Suitable polyamides of the present invention include water-soluble polyamides such as poly(diethylenetriamine adipamide), poly(diethylenetriamine glutaramide), poly(diethylenetriamine succinamide), poly(diethylenetriamine malonamide), poly(diethylenetriamine oxalamide), poly(diethylenetriamine fumaramide), poly(diethylenetriamine phenylmalonamide), poly(diethylenetriamine maleamide), poly(triethylenetetraamine adipamide), poly(triethylenetetraamine glutaramide), poly(triethylenetetraamine succinamide), poly(triethylenetetraamine malonamide), poly(triethylenetetraamine oxalamide), poly(tetraethylenepentaamine adipamide), poly(tetraethylenepentaamine glutaramide), poly(tetraethylenepentaamine succinamide), poly(tetraethylenepentaamine malonamide), poly(tetraethylenepentaamine oxalamide), poly(bis(hexamethylene)triamine adipamide), poly(bis(hexamethylene)triamine glutaramide), poly(bis(hexamethylene)triamine succinamide), poly(bis(hexamethylene)triamine malonamide), poly(bis(hexamethylene)triamine oxalamide), poly(triethyleneamine malonamide), poly(tetraethyleneamine malonamide) or mixtures thereof.
Suitable water-insoluble polyamides include poly(ethylene adipamide), poly(ethylene glutaramide), poly(ethylene succinamide), poly(ethylene malonamide), poly(ethylene oxalamide), poly(hexamethylene adipamide) or mixtures thereof.
In addition, the reaction temperature for preparing polyamides of the present invention is from about 24xc2x0 C. to 130xc2x0 C., and most preferably from about 50xc2x0 C. to 100xc2x0 C.
The process for preparing polyamides of the present invention may be substantially solvent-free or in the presence of at least one solvent. Such solvent includes methanol, ethylene glycol, glycerol, ethanol, t-butanol, isopropanol, water/NaCl, water/(NH4Cl), water/(NH4)3SO4, water/NH4NO3, water/(NH4)PO4 or mixtures thereof.
In a preferred embodiment of the invention, R is a C2 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 alkyl group, R4 is a C2 alkyl group, is NH, n is 1, the reaction temperature is from about 50xc2x0 C. to 100xc2x0 C. and the reaction is substantially in the absence of solvent.
In another preferred embodiment of the invention, R is xe2x80x94CH2CH2CH2CH2xe2x80x94, R1 is CH3, and R2 is CH3, wherein the polyamide is prepared in the presence of an immobilized hydrolytic enzyme derived from Candida antarctica, and the enzyme is present from about 0.5% to 3% by weight of enzyme based on the total weight of the diester and polyamine.
Another object of the present invention is to provide a polyamide which is the enzymatic reaction product of at least one polyamine and at least one diester, and having the general formula:
[NHCOxe2x80x94Rxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(A)]m
or
xe2x80x83[NHCOxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(A)]m,
wherein when A is [Xxe2x80x94(CH2)k]n, X is selected from one or none of heteroatom or non-heteroatom, wherein the non-heteroatom comprises amine, thiol, carbonyl, carboxyl or C1 to C6 hydrocarbyl group selected from one of alkanol, alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene or alkenyl; R is a C1 to C20 hydrocarbyl group selected from one of alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; n is 0 to 40; k is 1 to 6; and m is greater than or equal to 5;
wherein when A is 
R is a C1 to C20 hydrocarbyl group selected from one of alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; n is 1 to 6; k is 1 to 6; and m is greater than or equal to 5; and
wherein when A is 
R is a C1 to C20 hydrocarbyl group selected from one of alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene, alkenyl or mixtures thereof; n is 1 to 6; k is 1 to 6; and m is greater than or equal to 5.
In one embodiment of the invention, when the polyamide is
[NHCOxe2x80x94Rxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(Xxe2x80x94(CH2)k)n]m,
R is xe2x80x94CH2CH2CH2CH2xe2x80x94, X is O, n is 3, k is 2, and m is greater than 5; or R is CH2xe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5; or R is CH(C6H5)xe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5; or R is CHxe2x95x90CHxe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5.
In another embodiment of the invention, when the polyamide is
xe2x80x83[NHCOxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(Xxe2x80x94(CH2)k)n]m,
X is O, n is 3, k is 2, and m is greater than 5; or X is NH, n is 1, k is 2, and m is greater than 5.
Additionally, in one embodiment, the polyamide of the present invention is 
R is CH2xe2x80x94, k is 2, n is 1, and m is greater than 5; or R is CH(C6H5)xe2x80x94, k is 2, n is 1, and m is greater than 5; or R is CHxe2x95x90CHxe2x80x94, k is 2, n is 1, and m is greater than 5; alternatively, when the polyamide is 
k is 2, n is 1, and m is greater than 5.
Further, in one embodiment of the invention, the polyamide is 
R is CH2, k is 2, n is 1, and m is greater than 5; or R is CHC6H, k is 2, n is 1, and m is greater than 5; or R is CHxe2x95x90CH, k is 2, n is 1, and m is greater than 5;
Even further, in one embodiment of the invention, the polyamide is 
k is 2, n is 1, and m is greater than 5.
The polyamides of the present invention may have residues of at least one diester and at least one polyamine.
In addition, the final concentration of polyamides of the present invention in aqueous solution is preferably greater than about 1% by weight and most preferably greater than about 40% by weight.
In one embodiment of the invention, the polyamides may have a molecular weight polydispersity (Mw/Mn) range from about 2.2 to 3.0, molecular weight (Mw) range from about 4,000 to 12,000 Daltons, a molar ratio of the reactant ester group of the diester:reactant primary amine of the polyamine from about 0.95:1.1 to 1.1:0.95, and final concentration of polyamide in the aqueous solution is greater than about 40% by weight;
wherein the diester includes dimethyl malonate, dimethyl fumarate, dimethyl phenylmalonate or mixtures thereof; and
wherein the polyamine includes triethylene glycol diamine, ethylenediamine (EDA), bis(hexamethylene triamine) (BHMT), hexamethylenediamine (HMDA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), dipropylenetriamine (DPTA), tripropylenetriamine (TPTA), tetrapropylenepentamine (TPPA), N-methyl-bis-(aminopropyl)amine (MBAPA), spermine, spermidine, 1-phenyl-2,4-pentane diamine, 2-phenyl-1,3-propanediamine, phenylenediamine or mixtures thereof.
The polyamides of the present invention may also include residues of ezye equal to or less than about 2% by weight of the polyamide.
Another object of the present invention is to provide a cellulose slurry comprising cellulose fibers and polyamides of the present invention. The cellulose slurry may also contain residues of enzyme.
Still another object of the present invention is to provide wet strength resins, creping adhesives and cellulose products comprising the polyamides, and processes for preparing and using the same.
A cellulose product of the present invention is prepared by adding at least one polyamide which is the enzymatic product of at least one diester and at least one polyamine, to a cellulose slurry.
The cellullose slurry may include at least one additive, the additive comprising at least one of cellulose fibers, fillers, coagulants, flocculants, wet strength or dry strength binders, retention aids, surfactants, sizing agents, chemical softeners, clay, titanium dioxide, metal silicates and calcium carbonate.
The cellulose product of the present invention may further comprise enzyme equal to or less than about 2% by weight of the polyamide.
The cellulose product may also include nonionic polymer from about 1% to 0.005% by weight based on paper.
Additionally, the cellulose product of the present invention may include polyamide-epihalohydrin resin from about 1% to 0.005% by weight based on paper.
The polyamide-epihalohydrin resin is a reaction product of at least one polyamide of the present invention and at least one epihalohydrin.
The molar ratio of epihalohydrin:secondary amine of the polyamide is preferably from about 0.02:1 to 2:1, and most preferably from about 0.5:1 to 1.5:1.
Polyamide-epihalohydrin resins of the present invention have a molecular weight range preferably from about 4,000 to 2,000,000 Daltons, and most preferably from about 10,000 to 100,000 Daltons.
Suitable epihalohydrins include epichlorohydrin, epibromohydrin or epiiodohydrin.
The reaction temperature for preparing polyamide-eiphalohydrin resins of the present invention is from about 0xc2x0 C. to 90xc2x0 C.
The concentration of polyamide-epihalohydrin resin in aqueous solution is preferably from about 1% to 50%, and most preferably from about 10% to 15% by weight based on the total weight of the resin.
The Brookfield viscosity of the resin is preferably from about 1 to 1000 cps, and most preferably from about 10 to 200 cps.
The polyamide-epihalohydrin resin may include enzyme in an amount equal to or less than 2% by weight of the polyamide.
In a most preferred embodiment, the polyamide-epihalohydrin resin of the present invention has a molar ratio of epihalohydrin:secondary amine of the polyamide from about 0.5:1 to 1.5: 1, wherein the polyamide-epihalohydrin has a molecular weight range from about 10,000 to 100,000 Daltons; and the epihalohydrin is epichlorohydrin.
Furthermore, the polyamide-epihalohydrin resin may include at least one solvent selected from at least one of water/NaCl, water/Na2SO4, water/NaNO3, water/Na3PO4, water/NH4Cl, water/(NH4)3SO4, water/NH4NO3, water/(NH4)3PO4 or mixtures thereof.
A strengthening aid composition is also provided in the present invention comprising polyamide-epihalohydrin resin and at least one solvent.
The strengthening aid is applied to a surface such as cellulose fiber web or drying surface, or slurry.
The strengthening aid of the present invention is applied to a slurry in an amount preferably from about 1 to 100 lb/ton, and most preferably from about 10 to 30 lb/ton.
Additionally, a creping composition is provided comprising polyamide-epihalohydrin resin and at least one nonionic polymer.
Suitable nonionic polymers include poly(vinyl alcohol), polyacrylamide, poly(ethylene oxide), poly(vinylpyrrolidinone) or mixtures thereof.
The creping adhesive is in a solids aqueous solution having a concentration preferably from about 35% to 10% solids, and most preferably from about 25% to 20% solids.
The fraction of polyamide-epihalohydrin resin in the solids aqueous solution is preferably from about 1% to 50%, and most preferably from about 5% to 25% by weight.
The fraction of nonionic polymer in the solids aqueous solution is preferably from about 90% to 10%, and most preferably from about 60% to 40% by weight.
The creping adhesive may be in an aqueous, solid, dispersion or aerosol form.
The adhesive may further include an enzyme present at an amount equal to or less than about 2% by weight of the polyamide.
The creping adhesive is used to crepe cellulose webs comprising sequentially or substantially simultaneously applying at least one polyamide-epihalohydrin resin and at least one nonionic polymer to a surface such as a drying surface.
Still another object of the present invention is to prepare a polyamide at a temperature to range from about 24xc2x0 C. to 130xc2x0 C.
The present invention is directed to enzyme-catalyzed polyamides, and processes for producing polyamides by reacting at least one diester and at least one polyamine in the presence of a hydrolytic enzyme.
The process of the present invention is an enzymatic process that provides advantages over the existing chemical processes for industrial synthesis of polyamides. For example, the enzymatic process of the present invention may be carried out under milder conditions (e.g., ambient temperature) than the chemical processes, as known in the art. In addition, the process of the present invention produces an enzymatic reaction product with a narrower molecular weight distribution (Mw/Mn) than conventional chemical reaction products in the art. The enzyme can also be retrieved at the end of the process and optionally recycled, thus reducing production cost. Furthermore, the process of the present invention may occur in the presence or absence of solvents, whereas some chemical processes, as known in the art, require extraneous solvents which may reduce the pure yield and molecular weight of the polyamide. Preferably, the process of the present invention is carried out at low temperature and in the absence of solvents.
The enzymatic process of the present invention also provides polyamides with excellent purity that are otherwise poorly or cannot be produced by conventional chemical methods. Further, the enzymatic process of the present invention provides simple synthesis of high-molecular-weight polyamides, which are otherwise difficult to prepare using conventional chemica processes.
The polyamide of the present invention is the reaction product of at least one diester and at least one polyamine in the presence of a hydrolytic enzyme.
As used herein, the term xe2x80x9chydrocarbylxe2x80x9d refers to aliphatic, cycloaliphatic or aromatic. The hydrocarbyl groups are understood to include alkanol, alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene or alkenyl groups. Further, hydrocarbyl is understood to include saturated or unsaturated, cyclic, branched or linear, non-substituted hydrocarbyl groups, and saturated or unsaturated, cyclic, branched or linear, substituted hydrocarbyl groups, with the latter referring to the hydrocarbon portion bearing additional substituents, besides carbon and hydrocarbon. Preferred hydrocarbyl groups include alkyl (such as methyl or ethyl) or haloalkyl (such as halomethyl or haloethyl) groups, and most preferred hydrocarbyl groups include alkyl groups.
The term xe2x80x9ccellulosic fiber webxe2x80x9d refers to sheets of paper made by a process which includes forming a papermaking furnish, depositing the furnish onto a foraminous surface, removing water from the web, and adhering the sheet to a drying surface such as a Yankee Dryer, and removing the sheet by a creping blade such as a doctor blade, as described in U.S. Pat. No. 4,501,640 to Soerens.
In addition, the term xe2x80x9ccellulose productxe2x80x9d refers to paper products including tissue paper or paper towels made from cellulosic fiber web as defined above.
Further, the term xe2x80x9cheteroatomxe2x80x9d refers to an atom other than carbon. Preferably, the heteroatom is N, S, or O. More preferably the heteroatom is S or O, and most preferably the heteroatom is N. Alternatively, xe2x80x9cnon-heteroatomxe2x80x9d refers to atoms including amine, thiol, carbonyl, carboxyl, or C1 to C6 hydrocarbyl group selected from one of alkanol, alkyl, haloalkyl, alkylene, aryl, aralkyl, aralkylene, alkarylene, arylene or alkenyl. Preferably, the non-heteroatom is CH2,NH or N(CH3). More preferably, the non-heteroatom is NH or CH2, and most preferably the non-heteroatom is NH.
Furthermore, the term xe2x80x9csubstantiallyxe2x80x9d refers to essentially, in essence, or to a large extent. xe2x80x9cSubstantially simultaneously applyingxe2x80x9d refers to adding two substances to a surface with substantially no time difference and essentially at the same position. The two substances being added can be in the form of a mixture as well as separately, e.g., by adding one substance during the addition of the other. The term xe2x80x9csimultaneouslyxe2x80x9d refers to occurring at the same time, and the term xe2x80x9cindividuallyxe2x80x9d refers to singular or separate.
xe2x80x9cSequentially applyingxe2x80x9d refers to at least two different substances being individually added to different locations on a machine used to prepare cellulose products. These locations are far away enough so that the one substance added is mixed with the cellulose slurry before another substance is added.
Diesters suitable for use in the present invention include those with the general formula:
R1OOCxe2x80x94Rxe2x80x94COOR2
or
R1OOCxe2x80x94COOR2
wherein R is preferably a C1 to C20 hydrocarbyl group, more preferably R is a C1 to C6 hydrocarbyl group, and most preferably, R is a C2 to C4 hydrocarbyl group. R1 is preferably a C1 to C22 hydrocarbyl group, more preferably, R1 is a C1 to C6 hydrocarbyl group, and most preferably R1 is a C1 to C2 hydrocarbyl group. R2 is preferably a C1 to C22 hydrocarbyl group, more preferably R2 is a C1 to C6 hydrocarbyl group, and most preferably R2 is a C1 to C2 hydrocarbyl group.
The diesters of the present invention have a molecular weight (Mw) range preferably from at least about 100 to 1200 Daltons, more preferably from at least about 100 to 600 Daltons, and most preferably from at least about 100 to 300 Daltons.
The diesters of the present invention include, but are not limited to, dialkyl malonate, dialkyl fumarate, dialkyl maleate, dialkyl adipate, dialkyl glutarate, dialkyl succinate, dialkyl oxalate, dialkyl phenylmalonate, or mixtures thereof.
Suitable polyamines include those with the following formula,
H2Nxe2x80x94R3xe2x80x94[Xxe2x80x94R4]nNH2
where R3 is preferably a C1 to C6 hydrocarbyl group, more preferably R3 is a C2 to C4 hydrocarbyl group, and most preferably R3 is a C2 hydrocarbyl group. R4 is preferably a C1 to C6 hydrocarbyl group, more preferably R4 is a C2 to C6 hydrocarbyl group, and most preferably R4 is a C2 hydrocarbyl group. X is selected from one or none of heteroatom or non-heteroatom. Preferably X is O, CH2, NH, N(CH3) or S, more preferably X is O, CH2 or NH, and most preferably X is NH. xe2x80x9cOne or none ofxe2x80x9d refers to X being present as a heteroatom or non-heteroatom, or X may not be present in the formula. The number of the repeating unit is represented by n, ranging preferably from 0 to 40, more preferably n is 1 to 5, and most preferably n is 1.
In a more preferred embodiment, R3 is a C2 to C4 hydrocarbyl group, n is 1 to 5, and X is CH2, NH, or O. Most preferably, R3 is a C2 hydrocarbyl group, n is 1, and X is NH.
In another more preferred embodiment, R4 is a C2 to C4 hydrocarbyl group, n is 1 to 5, and X is CH2, NH, or O. Most preferably, R4 is a C2 hydrocarbyl group, n is 1, and X is NH.
The polyamines of the present invention have a molecular weight (Mw) range preferably from at least about 40 to 10,000 Daltons, more preferably from at least about 40 to 5,000 Daltons, and most preferably from at least about 40 to 2,500 Daltons.
The polyamines of the present invention include, but are not limited to, polyalkylpolyamine, polyalkylenepolyamine, polyaralkylenepolyamine, polyalkarylenepolyamine, polyarylenepolyamine or mixtures thereof.
The polyamines preferably include, but are not limited to, ethylenediamine (EDA), triethylene glycol diamine, bishexamethylenediamine (BHMT), hexamethylenediamine (HMDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TPPA), dipropylenetriamine (DPTA), tripropylenetetramine (TPTA), tetrapropylenepentamine (TPPA), N-methyl-bis-(aminopropyl)amine (MBAPA), spermine, spermidine, 1-phenyl-2,4-pentanediamine, 2-phenyl-1,3-propanediamine, phenylene diamine or mixtures thereof.
More preferably, the polyamines of the present invention include, but are not limited to, triethylene glycol diamine, diethylenetriamine (DETA), triethylenetetraamine (TETA), dipropylenetriamine (DPTA), tripropylenetetraamine (TPTA), tetrapropylenepentamine (TPPA), N-methyl-bis-(aminopropyl)amine (MBAPA) or mixtures thereof.
Most preferably, the polyamines of the present invention include, but are not limited to, diethylenetriamine (DETA), triethylenetetraamine (TETA) or mixtures thereof.
In a preferred embodiment of the invention, R is a C1 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 to C6 alkyl group, R4 is a C2 to C6 alkyl group, X is CH2, O, S or NH, and n is 1 to 5.
In another preferred embodiment of the invention, R is a C2 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 alkyl group, R4 is a C2 alkyl group, X is NH, and n is 1.
In still another preferred embodiment of the invention, R is a C2 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 alkyl group, R4 is a C2 alkyl group, X is NH, n is 1, the reaction temperature is from about 50xc2x0 C. to 100xc2x0 C. and the reaction is substantially in the absence of solvent.
Further, in another preferred embodiment of the invention, R is xe2x80x94CH2CH2CH2CH2xe2x80x94, R1 is CH3, and R2 is CH3, wherein the polyamide is prepared in the presence of an immobilized hydrolytic enzyme derived from Candida antarctica, and the enzyme is present from about 0.5% to 3% by weight of enzyme based on the total weight of the diester and polyamine.
The hydrolytic enzyme of the present invention can be any hydrolytic enzyme or mixture of enzymes derived from synthetic or natural sources. The term xe2x80x9chydrolyticxe2x80x9d refers to cleavage of a bond, such as a peptide, ester or amide bond, by the addition of the elements of water, yielding two or more products. Synthetic sources of the hydrolytic-enzyme of the present invention include, but are not limited to, peptide synthesizer or expression vector. Natural sources of the hydrolytic enzyme of the present invention include, but are not limited to, animals, plants, bacteria, yeast, fungi or virus. Preferably, the enzyme is obtained from a natural source including, but are not limited to, Candida species such as Candida antarctica, Pseudomonas species such as Pseudomonas fluorescence, Mucor species such as Mucor miehei or Rhizomucor miehei. Most preferably, the enzyme is obtained from Candida antarctica. 
The hydrolytic enzyme may be free or immobilized. The term xe2x80x9cimmobilizedxe2x80x9d refers to the enzyme being bound to an inert carrisuch as acrylic or polyurethane resin, or entrapped in an inert polymer such as Celite. Preferably, the hydrolytic enzyme is immobilized. The immobilized enzyme may be removed from the reaction mixture after completion of the polymerization and optionally reused in another reaction.
Furthermore, the hydrolytic enzyme may be fully or partially active. The hydrolytic enzyme of the present invention preferably includes, but is not limited to, lipase, esterase, protease or mixtures thereof. More preferably, the enzyme is lipase, protease or mixtures thereof. Most preferably, the enzyme is lipase. An example of lipase includes palatase. A Commercial example of lipase includes Novozym(copyright) 435 (available from Novo Nordisk).
The presence of enzyme is required in the process of the present invention. The amount of enzyme used in the present invention is preferably from about 0.01% to 10%, more preferably from about 0.1% to 5%, and most preferably from about 0.5% to 3% by weight based on the total weight of the diester and polyamine. The amount of enzyme used in the process of the present invention is critical. For instance, if less than 0.01% of enzyme is used, the polymeric reaction would be slowed down and result in a lower molecular weight product. If more than 10% of enzyme is used, the polymeric reaction would result in a much higher molecular weight product.
The enzyme used in the process of the present invention can be removed or denatured during or after completion of the reaction.
Polyamides of the present invention are prepared in a process involving polymerization of diester and polyamine reactants in the presence of enzyme-under mild conditions, and in the absence or presence of solvents. The reaction product is optionally dissolved in an aqueous solution, and the enzyme is optionally removed. The process of the present invention allows polymerization of reactants under mild conditions to provide high molecular weight (Mw) polyamides with a relatively narrow molecular weight distribution or molecular weight polydispersity (Mw/Mn).
The molar ratio of the reactant ester group of the diester to the reactant primary amine group of the polyamine may be approximately equal molar ratio. However, the reaction may be carried out with reactants in stoichiometric imbalance. The molar ratio of the reactant ester group of the diester: reactant primary amine group of the polyamine is preferably from about 0.8:2 to 2:0.8, more preferably from about 0.90:1.1 to 1.1:0.90, and most preferably from about 0.95:1.1 to 1.1:0.95.
In one embodiment of the invention, the molar ratio of reactants may be adjusted to produce a polyamide with terminal amine units. Such polyamides may be useful in the synthesis of other polymers. The molar ratio of the reactant ester group of the diester: reactant primary amine group of the polyamine is preferably from about 1:1.01 to 1:2, more preferably from about 1:1.02 to 1:1.5, and most preferably from about 1:1.03 to 1:1.06.
In a preferred embodiment, polyamides having high molecular weights and/or which cannot be made chemically, may be prepared by the enzymatic process of the present invention. Examples of preparation of such polyamides include the enzymatic reaction of malonic acid and diethylene triamine, fumaric acid and diethylene triamine, or maleic acid and diethylene triamine, to form a high-molecular-weight polymer.
The process of the present invention is preferably performed at a reaction temperature from about 24xc2x0 C. to 130xc2x0 C., more preferably from about 40xc2x0 C. to 110xc2x0 C., and most preferably from about 50xc2x0 C. to 100xc2x0 C.
If the polyamide is prepared using at least one solvent, the solvents and any byproduct molecules produced by the reaction may be removed during or after the reaction under normal or reduced atomospheric pressure, or by evaporating at from about 70xc2x0 C. to 100xc2x0 C.
As discussed, the process of the present invention may occur in the absence or presence of solvent. Examples of solvents preferably include, but are not limited to, methanol, ethylene glycol, glycerol ethanol, t-butanol, isopropranol, water/NaCl, water/Na2SO4, water/NaNO3, water/Na3PO4, water/NH4Cl, water/(NH4)3SO4, water/NH4NO3 and water/(NH4)3PO4. More preferably, the solvent includes methanol, ethanol, ethylene glycol, glycerol, water/NaCl and water/Na2SO4, and most preferably the solvent includes methanol, ethanol and ethylene glycol. For economic reasons, the process of the present invention is preferably performed in the absence of solvent.
Certain solvents such as ethylene glycol or glycerol can be added to the process of the present invention to prevent any solidification that may occur from about 50xc2x0 C. to 80xc2x0 C., as such solidification can slow down the polymerization reaction.
In a most preferred embodiment of the invention, R is a C2 to C4 alkyl group, R1 is a C1 to C2 alkyl group, R2 is a C1 to C2 alkyl group, R3 is a C2 alkyl group, R4 is a C2 alkyl group, X is NH, and n is 1, and the process has a reaction temperature from about 50xc2x0 C. to 100xc2x0 C., and occurs substantially in the absence of solvent.
In another most preferred embodiment, R is xe2x80x94CH2CH2CH2CH2xe2x80x94, R1 is CH3, and R2 is CH3, and the polyamide is prepared in the presence of a hydrolytic enzyme such as lipase derived from yeast Candida antarctica. The enzyme is immobilized, and present at an amount from about 0.5% to 3% by weight based on the total weight of the diester and polyamine.
The polyamides of the present invention may further comprise residues of the enzyme used in the reaction. In such a case, the amount of enzyme present is equal to or less than about 2%, more preferably equal to or less than about 1.5%, and most preferably equal to or less than about 1% by weight of the polyamide.
The polyamides of the present invention may also comprise residues of at least one diester and at least one polyamine from the reaction.
As discussed above, the present invention provides an enzymatic process for synthesizing polyamides from diester and polyamine monomers. The process allows synthesis of high molecular weight polyamides that are otherwise difficult to prepare using conventional chemical methods. Furthermore, the enzyme of the present invention may be recycled to reduce the cost of production. The polyamides prepared using the process of the present invention are high in molecular weight (Mw) as well as purity and yield. Although the polyamides may be linear or branched, the polyamides of the present invention are preferably linear and have a narrow molecular weight polydispersity (Mw/Mn). The polyamides of the present invention may also be water-soluble or water-insoluble. Preferably, the polyamides of the present invention are water-soluble.
The polyamide of the present invention include those having the following general formula:
[NHCOxe2x80x94Rxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(A)]m
or
[NHCOxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(A)]m,
wherein when A is [Xxe2x80x94(CH2)k]n, X is selected from one or none of heteroatom or non-heteroatom; R is a C1 to C20 hydrocarbyl group; n is 0 to 40; k is 1 to 6; and m is greater than or equal to 5;
when A is 
R is a C1 to C20 hydrocarbyl; n is 1 to 6; k is 1 to 6; and m is greater than or equal to 5; and
when A is 
R is a C1 to C20 hydrocarbyl; n is 1 to 6; k is 1 to 6; and m is greater than or equal to 5.
In a preferred embodiment, the polyamide of the present invention has the formula:
[NHCOxe2x80x94Rxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(Xxe2x80x94(CH2)k)n]m
when R is CH2CH2CH2CH2xe2x80x94, X is O, n is 3, k is 2, and m is greater than 5; or when R is CH2xe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5; or when R is CH(C6H5)xe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5; or when R is CHxe2x95x90CHxe2x80x94, X is NH, n is 1, k is 2, and m is greater than 5.
In another preferred embodiment, the polyamide of the present invention has the formula:
[NHCOxe2x80x94CONHxe2x80x94(CH2)kxe2x80x94(Xxe2x80x94(CH2)k)]m
when X is O, n is 3, k is 2, and m is greater than 5; or when X is NH, n is 1, k is 2, and m is greater than 5.
In still another preferred embodiment, the polyamide of the present invention has the following formula: 
when R is CH2xe2x80x94, k is 2, n is 1, and m is greater than 5; or when R is CH(C6H5)xe2x80x94, k is 2, n is 1, and m is greater than 5; or when R is CHxe2x95x90CHxe2x80x94, k is 2, n is 1, and m is greater than 5.
Further, in another preferred embodiment, the polyamide of the present invention has the formula: 
wherein k is 2, n is 1, and m is greater than 5.
Further, in still another preferred embodiment, the polyamide of the present invention has the following formula: 
when R is CH2, k is 2, n is 1, and m is greater than 5; or when R is CHC6H5, k is 2, n is 1, and m is greater than 5; or when R is CHxe2x95x90CH, k is 2, n is 1, and m is greater than 5.
Even further, in another preferred embodiment, the polyamide of the present invention has the following formula: 
wherein k is 2, n is 1, and m is greater than 5.
Polyamides of the present invention includes water-soluble and water-insoluble polyamides.
The water-soluble polyamides of the present invention include Poly(diethylenetriamine adipamide), poly(diethylenetriamine glutaramide), poly(diethylenetriamine succinamide), poly(diethylenetriamine malonamide), poly(diethylenetriamine oxalamide), poly(diethylenetriamine fumaramide), poly(diethylenetriamine phenylmalonamide), poly(diethylenetriamine maleamide), poly(triethylenetetraamine adipamide), poly(triethylenetetraamine glutaramide), poly(triethylenetetraamine succinamide), poly(triethylenetetraamine malonamide), poly(triethylenetetraamine oxalamide), poly(tetraethylenepentaamine adipamide), poly(tetraethylenepentaamine glutaramide), poly(tetraethylenepentaamine succinamide), poly(tetraethylenepentaamine malonamide), poly(tetraethylenepentaamine oxalamide), poly(bis(hexamethylene)triamine adipamide), poly(bis(hexamethylene)triamine glutaramide), poly(bis(hexamethylene)triamine succinamide), poly(bis(hexamethylene)triamine malonamide), poly(bis(hexamethylene)triamine oxalamide), poly(triethyleneamine malonamide), poly(tetraethyleneamine malonamide) or mixtures thereof.
The water-insoluble polyamides of the present invention include poly(ethylene adipamide), poly(ethylene glutaramide), poly(ethylene succinamide), poly(ethylene malonamide), poly(ethylene oxalamide), poly(hexamethylene adipamide) or mixtures thereof.
The polyamides prepared by the process of the present invention are preferably dissolved in an aqueous solution. The final concentration of polyamides of the present invention in an aqueous solution is preferably greater than about 1% by weight, more preferably greater than about 10% by weight, and most preferably greater than about 40% by weight of the polyamide based on the total weight.
The polyamides of the present invention have a molecular weight polydispersity (Mw/Mn) range from about 1.2 to 5.0, preferably from about 2.0 to 4.0, and most preferably from about 2.2 to 3.0.
The polyamides of the present invention have a molecular weight (Mw) range preferably from about 1,000 to 60,000 Daltons, more preferably from about 2,000 to 20,000 Daltons, and most preferably from about 4,000 to 12,000 Daltons.
In one embodiment of the invention, the polyamides may have a molecular weight polydispersity (Mw/Mn) range from about 2.2 to 3.0, molecular weight (Mw) range from about 4,000 to 12,000 Daltons, a molar ratio of the reactant ester group of the diester:reactant primary amine of the polyamine from about 0.95:1.1 to 1.1:0.95, and final concentration of polyamide in the aqueous solution is greater than about 40% by weight; wherein the diester includes dimethyl malonate, dimethyl fumarate, dimethyl phenylmalonate or mixtures thereof; and wherein the polyamine includes triethylene glycol diamine, ethylenediamine (EDA), bis(hexamethylene triamine) (BHMT), hexamethylenediamine (HMDA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), dipropylenetriamine (DPTA), tripropylenetriamine (TPTA), tetrapropylenepentamine (TPPA), N-methyl-bis-(aminopropyl)amine (MBAPA), spermine, spermidine, 1-phenyl-2,4-pentane diamine, 2-phenyl-1,3-propanediamine, phenylenediamine or mixtures thereof.
Methods for determining the average molecular weight (Mw) of the polyamides of the present invention include, but are not limited to, size exclusion chromatography (SEC), solution viscosity or nuclear magnetic resonance (NMR).
In addition, analysis of the structure of polyamides of the present invention may be accomplished by any method known in the art. Preferably, such methods include, but are not limited to, infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, or carbon nuclear magnetic resonance (13C NMR) spectroscopy.
More preferably, such methods include, but are not limited to, SEC, IR, or 1H-NMR. Most preferably, such methods includes, but are not limited to, SEC, IR, or 1H-NMR.
Analysis of polyamides of the present invention by SEC, IR, 1H-NMR or 13C NMR may be performed according to conventional methods known to one of skill in the art.
The polyamides of the present invention can be used in the process of papermaking. Specifically, the polyamides of the present invention can be used in a composition as a strengthening aid and/or a creping adhesive to prepare cellulos products.
The polyamides of the present invention may be reacted with epihalohydrin to form a polyamide-epihalohydrin resin that can be used in preparing cellulose products. The polyamide-epihalohydrin resin of the present invention can be used in the papermaking process for applications including strengthening aid and/or creping adhesive.
The polyarnide-epihalohydrin resin of the present invention includes thermosetting or non-thermosetting resins.
The polyamide-epihalohydrin resin of the present invention is prepared according to methods known in the art. The polyamide-epihalohydrin resin of the present invention is prepared in a one step process comprising reaction of at least one polyamide and at least one epihalohydrin in an aqueous medium. The reaction temperature range is preferably from about 0xc2x0 C. to 90xc2x0 C. More preferably, the temperature range is from about 50xc2x0 C. to 70xc2x0 C., and most preferably the temperature range is from about 55xc2x0 C. to 65xc2x0 C. The reaction is allowed to proceed until the desired molecular weight of the resin is achieved. The reaction is then optionally diluted and/or stabilized at an acidic pH with added acid.
The epihalohydrin of the present invention includes, but is not limited to, epichlorohydrin, epibromohydrin or epiiodohydrin. Preferably, the epihalohydrin is epichlorohydrin.
The molar ratio of epihalohydrin:secondary amine of the polyamide is preferably from about 0.02:1 to 2:1. More preferably, the molar ratio of epihalohydrin:secondary amine of the polyamide is from about 0.1:1 to 1.8:1. Most preferably, the molar ratio of epihalohydrin:secondary amine of the polyamide is from about 0.5:1 to 1.5:1.
The polyamide-epihalohydrin resin of the present invention has a molecular weight (Mw) range preferably from about 4,000 to 2,000,000 Daltons, more preferably from about 8,000 to 800,000 Daltons, and most preferably from about 10,000 to 100,000 Daltons.
The concentration of polyamide-epihalohydrin resin in an aqueous solution is preferably from about 1% to 50%, more preferably from about 5% to 25%, and most preferably from about 10% to 15% by weight based on the total weight of the resin.
In a most preferred embodiment, the polyamide-epihalohydrin resin of the present invention has a molar ratio of epihalohydrin:secondary amine of the polyamide from about 0.5:1 to 1.5:1, and wherein the polyamide-epihalohydrin has a molecular weight range from about 10,000 to 100,000 Daltons, and the epihalohydrin is epichlorohydrin.
The viscosity of the polyamide-epihalohydrin resin may be determined using methods known in the art such as the Gardner-Holdt method or Brookfield method. When using the Gardner-Holdt method, the sample is removed from the reaction vessel (e.g., approximately 15 g) and cooled to about 25xc2x0 C. The sample is then transferred to a Gardner tube and brought up to the level of the first mark on the tube. The tube is then corked leaving an air space above the liquid. The sample tube is inverted and the rate of bubble rise in the sample tube is compared to the bubble rise in a set of Gardner-Holdt standards designated xe2x80x9cAxe2x80x9d (low viscosity) to xe2x80x9cZxe2x80x9d (high viscosity). The standards are kept at 25xc2x0 C. Once the desired Gardner-Holdt viscosity is reached, the resin can be diluted and the pH adjusted as necessary.
When the Brookfield method is used, the Brookfield viscosity is determined using a DV-I viscometer (Brookfield Viscosity Lab, Middleboro, Mass.). The process for determining the Brookfield viscosity includes attaching a spindle (number 2) to the viscometer which is set at a speed of 30 rotations per minute (rpm). A solution comprising 12.5% by weight of the polyamide composition is prepared. The spindle is then put into the solution and stirred at 30 rpm for 3 minutes at ambient temperature. The viscosity is then recorded in centipoises (cps). Preferably, the viscosity of the polyamide-epihalohydrin resin is determined using the Brookfield method.
The polyamide-epihalohydrin resin of the present invention has a Brookfield viscosity range preferably from about 1 to 1000 cps at 12.5% concentration in water. More preferably, the polyamide-epihalohydrin resin of the present invention has a Brookfield viscosity range from about 5 to 500 cps. Most preferably, the polyamide-epihalohydrin resin of the present invention has a Brookfield viscosity range from about 10 to 200 cps.
As discussed above, the polyamide-epihalohydrin resin of the present invention can be used as a strengthening aid to prepare cellulose products. Strengthening aids are generally used in papermaking to enhance the strength of the paper web. In particular, the polyamide-epihalohydrin resin of the present invention may be used as a strengthening aid to fortify cellulosic fiber webs in the process of papermaking.
The concentration of polyamide-epihalohydrin in an aqueous solution of strengthening aid is preferably from about 1% to 50% by weight, more preferably from about 5% to 25%, and most preferably from about 10% to 15% by weight.
The strengthening aid of the present invention may be a wet or dry strength agent. Further, the strengthening aid may be added directly or indirectly to the cellulosic fiber web.
The strengthening aid of the present invention may be applied onto the surface of the Yankee dryer (e.g., spraying), after which the cellulosic fiber web is pressed onto the dryer surface. In addition, the strengthening aid of the present invention may be applied onto the surface of the Yankee dryer alone or simultaneously with a creping adhesive formulation.
The strengthening aid of the present invention may also be added to a paper furnish or cellulosic slurry in an amount preferably from about 1 to 100 lb/ton, more preferably from about 5 to 50 lb/ton, and most preferably from about 10 to 30 lb/ton.
The use of the polyamide-epihalohydrin resin of the present invention as a strengthening aid to prepare cellulose products provides strong wet strength and dry strength properties, as well as fine paper qualities and excellent paper machine runnability.
Furthermore, the polyamide-epihalohydrin resin of the present invention can be used as a creping adhesive in preparing cellulose products. In particular, the creping adhesive can be used in a creping process to prepare cellulose products.
The creping process of the present invention can include the steps of applying the creping adhesive to a drying surface, preferably the surface of a Yankee Dryer, to provide a fibrous web, adhering the web to the drying surface by pressing the fibrous web against the surface, and creping the fibrous web with a creping device to dislodge it from the drying surface. Preferably, the creping device is a doctor blade.
The creping adhesive compositions of the present invention are obtained from the reaction of polyamide-epihalohydrin resin and nonionic polymer.
The nonionic polymer of the present invention includes, but is not limited to, poly(vinyl alcohol), polyacrylamide, poly(ethylene oxide), poly(vinylpyrrolidinone) or mixtures thereof. Preferably, the nonionic polymer is poly(vinyl alcohol).
As described herein, the term xe2x80x9csolidsxe2x80x9d refers to the amount (in grams) of materials that are the active components or active ingredients of the present invention per gram of solution. The creping adhesives of the present invention are in an aqueous solution with solids content of polyamide-epihalohydrin and nonionic polymer.
The final concentration of solids in the aqueous solution is preferably from about 35% to 10% solids, more preferably from about 30% to 15% solids, and most preferably from about 25% to 20% solids.
The fraction of polyamide-epihalohydrin resin in the solids is preferably from about 1% to 50% by weight, more preferably from about 1% to 40% by weight, and most preferably from about 5% to 25% by weight.
The fraction of nonionic polymer in the solids is preferably from about 90% to 10% by weight, more preferably from about 75% to 25% by weight, and most preferably from about 60% to 40% by weight.
The application of creping adhesive of the present invention can be done in any manner known in the art, and in forms comprising aqueous, solid, dispersion or aerosol. Preferably, the creping adhesive is in the form of an aqueous solution or dispersion. The methods of application comprise simultaneous or sequential application of the polyamide-epihalohydrin and nonionic polymer to a drying surface or web to form the creping adhesive.
In addition, the creping adhesive can be added at the wet end of the paper machine or in the cellulose slurry. The cellulose slurry may comprise other additives such as cellulose fibers, fillers, coagulants, flocculants, wet strength or dry strength binders, retention aids, surfactants, sizing agents, chemical softeners, clay, titanium dioxide, metal silicates and calcium carbonate.
The creping adhesive compositions can also be used in conjunction with additives such as release agents, modifiers, surfactants, salts to adjust the water hardness, and/or acids or bases to adjust the pH of the creping adhesive composition, or other useful additives known in the art.
The use of the polyamide-epihalohydrin resin of the present invention as a creping adhesive to prepare cellulose products provides strong wet strength and dry strength properties, fine paper qualities and excellent paper machine runnability while increasing adhesion, dispersibility and uniform weting, as well as fine paper qualities and excellent paper machine runnability.
Further, when the polyamide-epihalohydrin resin of the present invention is used as a creping adhesive to prepare a cellulose product, the polyamide-epihalohydrin resin present in the cellulose product is preferably from about 1% to 0.005%, more preferably from about 0.5% to 0.05%, and most preferably from about 0.25% to 0.1% by weight based on paper.
The nonionic polymer present in the cellulose product is preferably from about 1% to about 0.005%, more preferably from about 0.5% to 0.05%, and most preferably from about 0.25% to 0. 1% by weight based on paper.
In addition, the strengthening aid of the present invention may be included with the creping adhesive formulation and then applied to the cellulosic fiber web.
When used as a strengthening aid, the polyamide-epihalohydrin resin present in the cellulose product is preferably from about 1% to 0.005%, more preferably from about 0.5% to 0.05%, and most preferably from about 0.25% to 0.1% by weight based on paper.
In the process for making cellulose products, certain additives such as retention aids, surfactants, sizing agents, softeners, fillers, coagulants, flocculants, clay, titanium dioxide, metal silicates or calcium carbonate or mixtures thereof, may be present in the cellulose product of the present invention. Other material can be present in the cellulose product so long as it does not interfere with or counteract the advantages of the creping adhesive and/or strengthening aid of the present invention.
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent.